For evaluating a toxicity of a chemical substance using algae, it is necessary to prepare algal cells by performing primary and passage cultures based on cells maintained in a liquid culture, an agar medium, or the like, add the test substance to the prepared algal cells, and conduct a test. However, it is cumbersome and inconvenient to maintain algal cells and perform a passage culture for each test.
For eliminating this cumbersomeness, frozen algal cells (Non Patent Literatures 1 and 2, etc.) can be utilized. Thawing frozen algal cells immediately before a test and using the thawed algal cells can rapidly subject the algal cells to a test without passage cultures.